This invention relates to a two-cycle reciprocal, rotary, internal combustion engine. This engine adapts certain principles of the opposed piston engine and the free-piston engine, both of which operate on a two-cycle principle.
In the opposed piston engine, two pistons move in opposite directions in the same cylinder. The two pistons are connected by cranks to separate crank shafts which are generally geared to a common drive shaft. Usually, the air-fuel intake port is located in the common chamber adjacent the bottom stroke of one piston and the combustion exhaust port is located adjacent the bottom stroke of the opposite piston to provide a uniflow-scavenged system. A relatively high power output is in this engine obtainable from a relatively lightweight power plant. However, fuel inefficiencies and the crank drive losses reduce the advantages otherwise inherent in the opposed piston engine.
In the free-piston engine, opposed power pistons move in the same cylinder in a manner similar to the opposed piston engine. However, the power pistons are connected directly at the distal ends to larger compressor pistons in a separate chamber. This engine originally operated primarily as a compressor, but has evolved into a turbine engine utilizing exhaust gases from the power pistons as the driving gas. The compressor pistons supercharged the intake air for subsequent further compression in the combustion chamber for the power pistons. The high compression pressures in the combustion chamber permit the engine to operate with a fuel injection system. High compression ratios are possible since there are no bearing surfaces to be loaded as in a crank system. Limitation of the system to a turbine unit renders the engine useful generally for only large unit applications.
Other engines and pump units have certain operational features similar to the engine of this invention. For example, the NSU-Wankel engine is a rotary internal combustion engine utilizing a triangular rotating piston which is eccentrically mounted within a two lobed epitrochoid casing. The piston essentially forms a three chamber system from the triangular piston or rotor configuration. The eccentrically mounted rotor sequentially forms intake and compression, and combustion and exhaust functions as it rotates in the two lobes of the casing. This continuous sequential power process is similar in concept to the continuous sequential power process of the subject device.
A recently developed free piston, rotary engine utilizes certain operational features which are similar in principle to certain features of the subject device and, perhaps, is closest in general operating principle to the subject invention.
In this engine, called a rotary V engine, a plurality of cylinders are concentrically and symmetrically arranged in two sets around two separate axes of rotation. The axes intersect at a predetermined angle in the range of 20.degree. to 45.degree.. A single set of identical pistons each formed in a V configuration reciprocate in the two sets of cylinders, each piston having one free end slidably engaged in one cylinder of one set and its opposite free end slidably engaged in one cylinder of the other set. Each cylinder set is arranged in a separate cylindrical rotor housing with orthagonal transverse ends. The two rotor housings are retained within a stationary outer housing which enables cooperative rotation of each set of cylinders and contained piston ends within the stationary outer casing.
The central portion of each piston proximate the V-intersection of its two segments, is outside each of the two cylindrical housings. Because of the concentric arrangement of the respective segments of the V-pistons around the respective intersecting axes of rotation, the relative position of the piston ends in the two cylindrical rotor housings follows an elliptical locus as the rotor housings are rotated. In effect, the piston ends reciprocate within the cylinders although the junctures of the piston segments at the V-intersection remain co-planar.
The far ends of the rotor housings are capped and provided with the necessary valving and ignition systems to form a series of combustion chambers which are appropriately fired in continuous sequence to drive the two rotor housings around their respective axes.
While the several above described engines each have certain similarities to the subject engine, the subject engine as a whole differs substantially from each of the above described engines taken individually. Many of the undesirable features of the above-described engines, such as the use of cranks, complex seals, V-configurations, etc., are avoided by the subject engine.